Yu. M. Gledenov

Differential cross-section measurement for the {sup 6}Li(n,t){sup 4}He reaction at 3.67 and 4.42 MeV

Abstract A gridded ionization chamber was used to measure the differential cross sections for tritons from the 6Li(n,t)4He reaction at 3.67 and 4.42 MeV. Neutrons were produced via the D(d,n)3He reaction. The absolute neutron flux was determined through the 238U(n,f) and H(n,p) reactions. At 3.67 MeV the result is almost 90 deg symmetric, but it is obviously forward peaked at 4.42 MeV in the center-of-mass reference system.

Improving explosive nucleosynthesis models via (n,α) measurements

In explosive environments, (gamma,alpha) reactions constitute some of the most important links in the nucleosynthesis chains. However. it is very unlikely that the rates for most of these reactions will be determined by direct experiments and these rates also are currently very poorly constrained by theory. In this paper, we demonstrate that low-energy (n,alpha) measurements constitute an important new global technique for considerably reducing the uncertainties in (gamma,alpha) reaction rates.

Investigation of P-odd correlations in the capture of thermal polarized neutrons involving emission of secondary charged particles (technical issues)

Abstract An installation for measuring parity violation in reactions with polarized neutrons involving the emission of secondary charged particles is described. The main part of the experimental setup is a multisection proportional chamber operated in the current mode. The 6Li(n,α)3H and 10B(n,α)7Li reactions are studied. The P-odd asymmetry was measured with an accuracy of δ ∼ 5 × 10−8.

Differential cross-section measurement for the 64Zn(n,α)61Ni reaction at 5.03 and 5.95 MeV

Abstract Differential cross sections of the 64Zn(n,α)61Ni reaction were measured at neutron energies of 5.03 and 5.95 MeV by using a gridded ionization chamber. The experiment was performed at the 4.5-MV Van de Graaff accelerator of the Institute of Heavy Ion Physics, Peking University. Neutrons were produced through the D(d,n)3He reaction with a deuterium gas target. The absolute neutron flux was determined by the 238U(n,f) reaction and a calibrated BF3 long counter. Present results are compared with existing data.

Differential cross-section measurement for the 10B(n, α)7Li reaction

Abstract The differential cross sections of the 10B(n, α)7Li reaction were measured at 4.17, 5.02, 5.74, and 6.52 MeV by using a gridded ionization chamber. Neutrons were produced through the D(d,n)3He reaction. The absolute neutron flux was determined through the 238U(n,f) reaction. The experiment shows that as the neutron energy increases from 4.17 to 6.52 MeV, the differential cross section changes from almost 90-deg symmetry to obviously backward peaked in the center-of-mass reference system.

Total α-widths of neutron resonances of 147Sm and 149Sm

Abstract An investigation of the (n, α) reaction on 147 Sm and 149 Sm isotopes was performed in the energy range from 0 up to 400 eV and to 100 eV, respectively, using a multisectional proportional chamber. Values for the total α-widths or their upper limits were obtained for about 90 resonances. A comparison has been drawn between the obtained average α-widths and those predicted by optical and cluster models. In the case of 149 Sm, for resonances with spin 4 − the total α-width distribution was observed to be much narrower than expected from statistical theory. We failed to find a correlation between neutron and total α-widths.

Measurement of Differential Cross Section for the 64Zn(n,a)61 Ni Reaction at 2.54, 4.00, and 5.50 MeV

Abstract By using a twin-gridded ionization chamber, differential cross-section data of the 64Zn(n,α)61Ni reaction were measured at neutron energies of 2.54, 4.00, and 5.50 MeV. The experiment was performed at the 4.5-MV Van de Graaff accelerator of the Institute of Heavy Ion Physics, Peking University, China. Monoenergetic neutrons of 2.54 MeV were produced through the T(p,n)3He reaction with a solid Ti-T target, and those of 4.00 and 5.50 MeV were produced through the D(d,n)3He reaction with a deuterium gas target. The absolute neutron flux was determined through the 238U(n,f) reaction and a BF3 long counter was used as the neutron flux monitor. Results of the present work are combined with our previous data between 5.0 and 6.5 MeV and compared with other measurements and evaluations.

Discovery of a P-odd effect in triton emission from the reaction 6Li(n, α)3H

The results of measuring the P-odd asymmetry (Sn · Pt) for triton emission from the reaction 6Li(n, α)3H are presented. Here, Sn is the neutron spin and Pt is the triton momentum. Three series of measurements were performed, one at the Petersburg Nuclear Physics Institute (Gatchina, Russia) in a vertical neutron beam from the PWR reactor and two in the PF1B beam from the reactor at the Institute Laue-Langevin (Grenoble, France). On the basis of all three experiments, the P-odd asymmetry coefficient was found to be αPN = −(8.6 ± 2.0) × 10−8. The results of zero experiments and calculations give every reason to believe that the above P-odd asymmetry is due to the reaction being studied.

Angular distribution and cross-section measurements for 64Zn(n, α)61Ni reaction at 5.0, 5.7, and 6.5 MeV

Abstract Using a gridded ionization chamber, angular distributions for the 64Zn(n, α)61Ni reaction were measured at 5.0, 5.7, and 6.5 MeV. The neutrons were produced through the D(d,n)3He reaction. The neutron flux was determined through the 238U(n, f) reaction. The results show a backward peak in the center-of-mass reference system for 5.7 and 6.5 MeV. The cross sections are 72.5, 72.0, and 70.8 mb for 5.0, 5.7, and 6.5 MeV, respectively.

Cross sections of theZn67(n,α)64Ni reaction at 4.0, 5.0, and 6.0 MeV

Experimental cross section data of the {sup 67}Zn(n,{alpha}){sup 64}Ni reaction are very scanty because the residual nucleus {sup 64}Ni is stable and the commonly used activation method is not feasible. As a result, very large deviations (about 10 times) exist among different nuclear data libraries. In the present work, cross sections of the partial {sup 67}Zn(n,{alpha}{sub 0}){sup 64}Ni and total {sup 67}Zn(n,{alpha}){sup 64}Ni reactions are measured at neutron energies of 4.0 and 5.0 MeV for the first time, and those of 6.0 MeV are remeasured for consistency checking. A twin-gridded ionization chamber was used as the charged-particle detector and two enriched back-to-back-set {sup 67}Zn samples were adopted. Experiments were performed at the 4.5 MV Van de Graaff Accelerator of Peking University. Neutrons were produced through the {sup 2}H(d,n){sup 3}He reaction using a deuterium gas target. Absolute neutron flux was determined by counting the fission fragments from a {sup 238}U sample placed inside the gridded ionization chamber while a BF{sub 3} long counter was employed as neutron flux monitor. Present data are compared with results of previous measurements, evaluations, and talys code calculations.